Air conditioning system



AMI/Y7! M MM T! mw w/ w. w i M WM M. G. SHOEMAKER AIR conpmoumc SYSTEM Filed April 26, 1951 QQSSQ .Qmgi

Aug. 19, 1952 0 Patented Aug. 19,1952

I AIR CONDITIONING sYsa'EM Malcolm G; Shoemaker, Doylesto'y'vn, Pa., assi'gnor f0 Pliilo'cblpfifatidn, Philadelphia, a C01- poration of Pennsylvania Application April 26, msnsei-ial No. 222,953

in claims. (01. t2=3 This invention is concerned with refrigeration apparatus and, more partcularly, relates to control of the air cooling and dehumidification functions of such apparatus.

Broadly, the invention has for its primary object the provision .of control, or modulation, ofthe capacity of an air conditioner or' other refrigerating machine in such mannerthat the temperature of ambient or circulating air is maintained within a desired range, without undue sacrifice of the capacity of the: machine to effect the transfer of latent heat which results in condensation of undesired moisture present in the circulating air.

As is now well known in air conditionin practice, maintenance of a conditioned. space within theso-called. comfort zone" involves not-only control of the air dry bulb temperature; but'also limitation of the relative, humidity prevailing within said space. For example, under summer cooling conditions, the comfort zone is generally regarded as covering a range of relative humidi-" ties from about 70% to about 30%, the permis sible comfort zone temperatures ranging from 68 to 78, under the 70% condition,- and from 72' to 85, at the 30% condition.- Under high humidity conditions commonly encountered inclimates where room coolin is desirable, pull down of the air temperature to an acceptable value necessarily results in a very substantial increase in relative humidity of the air, and it will therefore be appreciated thatremoval of moisturefrom the air is essential to comfort. A relatively wide range of psychrometric conditions may exist in practice, and control of the capacity'of the air conditioning machine (as respects transfer of both sensible and latent heat) isthereforesSritial if the space being conditioned is to be'ke'ptin the comfort zone. v V

At times, particularly when the apparatusis being operated to cool a bedrooin at night, the dry bulb temperature of the circulating air may drop below the acceptable minimum and it is then desirable to; modulate" the capacity oftl're machine in such a way as to restore the desired temperature condition.

In large installations such'modulation'can con-'- veniently be provided by controlling the amount of moisture in; the air, to ofiset changesin coolin capacity. Similarlyin' largeinsta'llations 'refrig-i cratin effect can also conveniently be modulated by varying the number of compressor cylinders effective to pump'refriger'ant, or by manipulating dampers to regulate air flow. Not; uncommonly some regulation of refrigerating effect been" achievedbyvaryingthe speed of the compressor;

While control of both temperature "and humidf ity conditions is also a problemin the case of single room package type air conditioners; the foregoin solutions are not applicable for a variety of reasons, including cost considerations. Most single room air conditioners utilize a compressor having o'nly one cylinder and it is therefore apparent that modulation of capacity by varying thenumberof cylinders is not feasible. Cycling the motor compressor has also not proven to be a practical solution. The rapid increase in humiditywhich usually takes place during periodsof idleness of the compressor may cause the humidity to reach a value exceeding comfort zone limits, even though cycling can readily be ,utilized to maintain the drybulb temperature with in a; satisfactory range. Further, the variation in sound level which results from cycling the unit is highly objectionable, especially in bedroom applications. e a

Attempts have been made to meet the foregoing difliculties and to provide satisfactory ca-. pacity modulation of air conditioning equipment of, the simpler type to which this invention has particular reference, and. heretofore these attempts have usually involved provisionof means for varying the operation, of the air conditioning machine in such away that the temperature of the entire evaporator is raised to a-higher value in response to a predetermined reduction in the temperature of the circulating air. .However this expedient is also unsatisfactory, in view of the fact that there is no longerlsuflicientlimitation of humidity, andfor this reason, it is not possible to meet the comfort zone conditions. The truth of this will be recognized whenit is understood" continuation of operation of one of the units re-.

stilts in Variation in th sound level of the ma.- chine.v As pointed out above, such variation is objectionable. l

With the foregoing in mind, it is to be emphas'iz'ed that the present invention provides for modula'ting the capacity of refrigerating machines in such manner that the total air cooling capacity of the evaporator is reduced, when the temperature of the circulating air falls to a predetermined value, while yet continuing to maintain a portion of the evaporator at a temperature sumciently low to result in substantial condensation of moisture present in the air. It is particularly noteworthly that these advantageous results are achieved in a very simple manner and by the use of only a single room-cooling evaporator element operating at a single pressure throughout.

In the achievement of the foregoing general" ends the invention provides, in novel combination with the elements of an air conditioning system of known type, an auxiliary refrigeration circuit or system including: a tank or receiver adapted to receive liquid refrigerant flowing from the condenser; and associated restrictor and evaporator portions. Said tank and portions are connected in series circuit with the compressor, and the evaporator portion of said auxiliary system is disposed in high heat exchange relation with the high pressure side of the main refrigeration system. Means is provided for causing a portion of the liquid refrigerant derived from the condenser to flow through the auxiliary system, when reduction in total cooling capacity of the main evaporator is desired, with the. result that the main evaporator element is deprived of a certain amount of the liquid refrigerant which would' normally flow thereto and, as a consequence, only a portion of the main evaporator is supplied with liquid refrigerant and remains effective for cooling purposes. The portion which remains effective, however, continues to operate at a temperature approximately equal to the normal, unmodulatedtemperature of the overall evaporator, since no change occurs in the suction pressure of the machine, and thistemperature is, of course, sufficiently low to result in substantial condensation of moisture present in the circulating air. The extent of the evaporator portion which is deprived of liquidrefrigerant may be varied to any desired degree and, in theillustrated embodiment, this variation is advantageously controlled by movably or tiltably mounting the aforesaid tank or receiver, which tank is connected with both the main evaporator element and the evaporator portion of the auxiliary system. Tilting of the tank provides selective distribution of the condensed refrigerant between the said evaporator elemen and said evaporator portion.

The manner in which the objects and advantages of the invention may best be achieved will be more clearly understood from a consideration of the following description, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a diagrammatic representation of an air conditioning machine embodying the modulating apparatus of my invention, the aforesaid adjustable tank or receiver being shown in section; and, v

Figures 2 and 3 illustrate the tank in positions of adjustment other than that shown in Figure 1. Now making more detailed reference to the drawing, there is diagrammatically illustrated an air conditioning or refrigerating system including a pair of heat exchangers .IO .and H which, as shown, are of known finned coil type. A compressor I2 is connected in series flow circuit with said heat exchangers through the agency of suitable conduits including suction and discharge passages which appear in the drawing at M and flows to the tank, and a similar section or connection [3b. The latter provides for outflow of liquid from the tank and toward the evaporator element It, through capillary tube I30. Each of these sections terminates in a downwardly presented opening freely communicating with the interior of the tank or receiver, and it will be observed that an additional section of tubing of capillary size extends within the receiver. This additional section, illustrated at H, is also provided with a downwardly presented opening communicating with the space within the receiver, and forms an extension of a capillary passage I8 connected with a-conduit a portion of which (shown at [9) is disposed in heat exchange relation with the discharge line 15, and another portion of which (illustrated at Ma) provides an auxiliary suction line returning to the compressor 12. As will be understood, the conduit portion l!) constitutes the evaporator portion of the auxiliary circuit mentioned hereinabove. Further. and-more detailed reference to the receiver and the manner in which it is mountedwill be made hereinafter.

The illustrated embodiment further includes switching apparatus shown diagrammatically at 20 and through the agency of which the motor of-compressor l2 may be placed across the line L. As willbe understood, when the machine is "intended for use as an air conditioner, provisionwould be made for forcing air over the heat exchangers orcoils l0 and H, and to this end suitable fans and motors are commonly employed, These elements of the apparatus have been omitted from the drawing, since illustration and'description thereof are not necessary to an understanding of the present invention. It is, however, to be understood that air to be cooled and dehumidified is freely circulated in heat exchange relation with :the evaporator element 10 and, for purposes which will be set forth in what follows, in heat exchange relation with thermo-sensitive means which adjustably supports the tank or receiver [6.

While a showing of the air conditioner cabinet has: also been omitted, it will be appreciated that a cabinet would be provided having partition means serving to divide the same into separate chambers housing the evaporator I0 and the condenser II. A dashed line appears in Figure 1, and the evaporator lies to the left thereof. As is apparent from the legend applied to the drawing this portion of the apparatus is disposed upon the indoors side of the dashed line. The contheaforesaid tank or receiver 16, and. which means will now be more fully considered.

As mentioned above, the receiver i6 is mounted for tilting movements, in order to providefeed of :the liquid refrigerant selectively .to'different portions of the circuit, andpreferably the ree ceiver is adiustably supported by a. thermo-sensitive element which, as shown, take the form of s rip 2| of bi-metallic material, said strip being secured to the receiver [.6 and having a spirally connguredportion 22 the inner convolution of which .isflxedly secured to. .astud 23.9 The spirally configured strip portion isdisposed adjacent; the evaporator element It and in the path Of air flowing in heat exchange relation with said evaporator element. As will be under! stood without further description, changes in air temperature cause the lower end of the strip 2i to, he raised orlowered. Thus the tank'is somounteu as to be tilted or adjusted in response t9. the temperature of the air passing the evaporator element H1. As will more clearly appear in what follows. when this temperature has fallen to a predetermined lower value the strip2l tilts or rotates the receiver I 5 to a position such that a. controlled amount of liquid refrigerant flow ing to said receiver lay-passes the main evaporator element Ill and returns to the compressor through the auxiliary refrigeration system, in-

cluding the evaporator portion I9. 1 When the desired air temperature is re-established the tank is, of course, returned, to a position such that all or the major part of the liquid refrigerant is delivered to the main evaporaton It is to be understood that while such automatic control of the position of the receiver is preferred, the invention also contemplates use of manually operable means, or other expedients, for varying the position of the receiver. a

To accommodate the tilting movements of. the receiver, the restricted. passages, which extend thereintohave sufficient flexibility topermit free movement of the receiver without interfering with the flow of refrigerant throughjthepase sages, Suohaccomrnodation can conveniently be prov d d by including a flex-ibleloop of tub ne.

. h i I is, approximatelyequal .to the restriction 'pre sented'by-the circuit from the-said receiver; to: 'ixiliniy evaporator portion-l9;'and-=thence to the; suction side "of. the compressor through.

It is, 0f COlllSGpthe physical reiconduit [4a. strietion rather than the eifective restriction h is pre. eratly so proportioned. it being weight; which can pass throughv one ofthe' two paral el c u pass through the other path in the gaseous .-I peration ugnit' is llot essential that anathet n line-two evaporators' 1:0 and L9, :be'of the 1. 1 I'StQQQ at he amount. of refrigerant by:

.theliquid phase is many times. h quantityaot irefrigerantby.weight, which :will- I he receiver I 6 may occupy any an ular position 'hetween l the limiting positionsillustratediin. Figures 1 and-3. 3mi; considerationof the operation of the apparatus with respect to three positions of the receiver will sufiice-to illustrate the manner" in which the equipment functions. First making referenceto Figure-'1, it will be seen that the receiver I5 is. shown. in that figure as occupying a position in-which all of the liquid refrigerant flowing into said .receiver, through the connection 1.3a, passes to the main evaporator element [.0 through connection [3b and. thecapillary tubing I30, which is interposed between said connection, and theuevaporar. tor. Thus Figure 1 is illustrative of-the position which the receiver occupies when themain evaporator element is operating .at maximum capacle ity. When the, receiver is so positioned the con nection 13b is, immersed in, liquid refrigerant; as shown, and the connection H. which communicates with capillary tubi-ngiB and, the aux. iliary evaporator portion 19, is disposed above. the level of liquid refrigerant within the. receiver, with the result that the receiver operates as a flash gas separator, returning only gas, tothe compressor through the auxiliary circuit.

The position of the receiver which results in minimum capacity at the main evaporator is illustrated in Figure 3, and this will be under-- stood to bathe position in which substantially all of, the liquid refrigerant delivered to the receiver returns to the compressor through the. alternate or auxiliary circuit and only gas traverses the evaporator, since the connection 13b is then disposed above the level of liquid within the receiver. The liquid passing through the tubing l1 and i8 toward the compressor 12 is returned to the gaseous state, by virtue of-fiow! ing through evaporator portion 19, wherein, by, virtue of heat exchange between the said ortion and the warm gaseous refrigerant flow ng,

through the conduit l5 of the main refrigeration circuit, the liquid emitted from the capillary tube I8 is re-evaporated and returned to the; com pressor through suction conduit portion Mil.-

.Any quantity of r fr e ant w ic is; caused tow ou h the. a il a i cui Icy-passin the ma e a r res nts a d rect re ue:

t inthe effectiv a a yro the main evapo rator, and the significance. of this will be an: re d h it s under t od tha t e recei ery occupy i r e ia p t ons. ne o which is illustrated in Figure 2, in which both of theparallel paths are supplied with liquid refrigerant. Under such a conditiondue to the substantial equality of the restriction of thez twp,

perate-a a s ac e peratu a taslow asis obtained un e e m l u m dulated condition illustrated. in Figure; 1. {E le-1111 17 11017: tance of this in providing the necessary continu ance of removal of moisture. from the :air .Willbe understoodflwithout restatement,- and. is ;;to 1 be.

contrasted with arrangements hitherto knownin which throttling, and the like, resultedgini-ian; I increased pressuresini the main} evaporator with a consequent undesirable rincreasain fthe ,surfac'ef temperature thereof a f 1 anus, and in the light om'hs'jioigaagat;

scription, it will be understood that the present:

invention provides -;air conditioning or-nefrigscrating equipment of very simple type in which the total air cooling capacity of the main evaporator element may be controlled automatically, while yet maintaining a portion of said evaporator element at atemperature sufficiently low to continue substantial condensation of excess moisture present in the circulating air.

' While a preferred structural embodiment has been illustrated and described, it is to be borne in mind that said embodiment is susceptible of modification, without departing from the spirit of this invention. For example, the receiver 16 may readily be mounted for movements other than tilting movements. Further, it is to be understood that, in the broader aspect, the invention is characterized by providing for fiow of refrigerant through parallel circuits of approximately equal restriction, in order that the flow of refrigerant by volume may be substantially the same in the two circuits under any condition of operation, coupled with means for selective distribution of the liquid component of the refrigerant between the two parallel circuits. In this aspect of the invention, a variety of flow control means may be utilized and are contemplated. However it will be recognized that the invention contemplates such changes and modifications as properly come within the scope of the appended claims.

I claim:

1. In'refrigeration equipment: a main refrigeration system including compressor, condenser, restrictor and evaporator elements so connected in series flow circuit that evaporation of refrigerant occurs in said evaporator element with consequent cooling of an ambient medium; an auxiliary refrigeration system; and apparatus for adjusting the heat exchange capacity of said evaporator element, including a movably mounted receiver to which is delivered liquid refrigerant flowing from said condenser element, said receiver being provided with a pair of outlet passages one of which communicates with said evaporator element and the other of which communicates with said auxiliary system, movement of said receiver serving to control the supply of liquid refrigerant to the said outlet passages to provide selective distribution of the condensed refrigerant between said evaporator element and said auxiliary system.

2. In refrigeration equipment: a main refrigeration system including compressor, condenser, restrictor and evaporator eiements so connected in series flow circuit that evaporation of refrigerant occurs in said evaporator element with consequent cooling of an ambient medium; an auxiliary refrigeration system; apparatus for adjust ing the heat exchange capacity of said evaporator element, including a movably mounted receiver to which is delivered liquid refrigerant flowing from said condenser element, said receiver being so connected with said evaporator element and with said auxiliary system that movement of said receiver provides selective distribution of the condensed refrigerantbetween' other portion movable in response to changes in;

temperature of said medium and adapted to effect corresponding movement of said receiver.

4. In refrigeration equipment: a main refrigeration system including compressor, condenser. restrictor and evaporator elements so connected in series flow circuit that evaporation of refrigerant occurs in said evaporator element with consequent cooling of an ambient medium; an auxiliary refrigeration system; and apparatus. for adjusting the heat exchange capacity of said evaporator element, including a tiltable' receiver to which is delivered liquid refrigerantflow ing from said condenser element, said receiver being so' connected with said evaporator element and with said auxiliary system that tilting of said receiver provides selective distribution of the condensed refrigerant between said evaporator element and said auxiliary system. 1

5. In refrigeration equipment: a main refrigeration system including compressor, condenser, restrictor and evaporator elements soconnected in series flow circuit that evaporation of refrigerant occurs in said evaporator element with consequent cooling of an ambient medium; an auxiliary system including an evaporator-portion in communication with the suction side of said compressor element; and apparatus for ad justing the heat exchange capacity of said evaporator element, including a tiltable receiver 'to which is delivered liquid refrigerant flowing from said condenser element, said receiver being provided with a pair of spaced outlet passages one of which communicates with said evaporator element and the other of which communicates with said evaporator portion, tilting of said receiver serving to control the supply of liquid refrigerant to'the said outlet passages to provide selective distribution of the condensed refrigerant between said evaporator element and said evaporator-portion. 1

6. Refrigeration equipment in accordancefwith claim 5, and further including means responsive of refrigerant flow circuits connected in par'allel with said means and each including an'evapor ator, said circuits presenting approximately equal restriction whereby, in response to opera-- tion of said circulatingmeans, approximately equal quantities of refrigerant, by volume, flow through each of said circuits, and means provid-" ing', selective distribution of liquid and gaseous components of the circulating refrigerant between said two circuits, said I last means comprising a movably mounted receiver disposed to receive refrigerant from said circulating means and having a'pair of outlet passages each'of which communicates with a correspondingone of; said circuits, movement of said receiverrservingto' control the supply of liquid and gaseous refrigerant to the said outlet passage to provide the: stated selective distribution. I

8. Air conditioning equipment in accordance with claim '7, and further including thermosensitive means responsive to the temperature of air; cooled .by one of said evaporators and adapted to effect adjustment movements of said with the temperature of receiver in accordance such air. a V

9. In refrigeration equipment, a main refriger ationsystem including compresson'condensr,

restrictor, and evaporatorelements so connected"- -in series flow circuit, that condensation'iof re frigerant occurs in said condenser element and evaporation of refrigerant occurs in said evaporator element with consequent cooling of ambient air, and apparatus for reducing the total air cooling capacity of said evaporator element while yet maintaining a part of said element at a temperature sufficiently low to result in substantial condensation of moisture present in the ambient air, said apparatus comprising: an auxiliary refrigeration system in circuit with said compressor element and including an evaporator connected in parallel with said main refrigeration system; and means including a chamber providing for volatilization of a portion of the liquid refrigerant discharged from said condenser element, and also providing for selective and controllable delivery, to said evaporator element and to the evaporator portion of said auxiliary system, of the gaseous and liquid refrigerant components available at said means.

10. In refrigeration equipment: a main refrigeration system including compressor, condenser, restrictor and evaporator elements so connected in series flow circuit that evaporation of refrigerant occurs in said evaporator element with consequent cooling of an ambient medium; an

auxiliary refrigeration system presenting restriction approximately equal to the restriction of said main refrigeration system; and apparatus for adjusting the heat exchange capacity of said evaporator element, including a movably mounted receiver to which is delivered liquid refrigerant flowing from said condenser element, said receiver being so connected with said evaporator element and with said auxiliary system that movement of said receiver provides selective distribution of the condensed refrigerant between said evaporator element and said auxiliary system.

MALCOLM G. SHOEMAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

